1. Field of the Invention
The present invention relates to a method of manufacturing a liquid ejection head.
2. Description of the Related Art
There has been proposed a liquid ejection head having such a shape that an ejection orifice forming member is recessed with respect to the surface of the ejection orifice forming member in the vicinity of an ejection orifice (Japanese Patent Publication No. H07-29437 and Japanese Patent No. 4498363). Such a shape can reduce damage caused by rubbing of liquid adhering to the surface of the head or damage on the ejection orifice caused by collision of paper to the head due to a paper conveyance error, and hence the liquid ejection head having the above-mentioned shape has a longer life. On the other hand, in Japanese Patent No. 3143307, there is disclosed a method of manufacturing a liquid ejection head, including forming a mold in a part to be formed into a flow path of liquid, applying a liquid resin material so as to cover the mold by spin coating to form the ejection orifice forming member, and removing the mold.
The ejection orifice forming member of the liquid ejection head has multiple ejection orifices formed therein, and liquid droplets are caused to fly from the ejection orifices to obtain a printed matter. The thickness of the ejection orifice forming member affects the volume and flying speed of the liquid droplets that are caused to fly from the ejection orifices. Therefore, when fluctuations in thickness of the ejection orifice forming member are large, the quality of the printed matter reduces. Therefore, it is preferred that the fluctuations in thickness of the ejection orifice forming member be small. On the other hand, as the method of manufacturing a liquid ejection head having such a shape that the ejection orifice forming member is recessed with respect to the surface of the ejection orifice forming member in the vicinity of the ejection orifice, there are known a method involving using electroforming (Japanese Patent Publication No. H07-29437), a method involving subjecting a photosensitive resin to weak exposure and heat treatment in combination (Japanese Patent No. 4498363), or the like.
However, the ejection orifice forming member formed by those methods has large fluctuations in thickness of the ejection orifice forming member, which affects the printing quality. In the method disclosed in Japanese Patent Publication No. H07-29437, when electroforming is carried out, a difference is easily generated in applied current amount between the center and the outer periphery of the substrate, and hence the metal film to be formed is liable to have different thicknesses. Further, in the method disclosed in Japanese Patent No. 4498363, during a time period from exposure via heat treatment to development for forming the recessed portion, the acid diffusion degree is liable to vary in the exposed region, and hence the depth of the recess is liable to fluctuate. Further, it is also conceivable to apply a method disclosed in Japanese Patent No. 3143307 to employ a method involving forming a recessed portion in the mold in advance, and then forming the ejection orifice forming member by spin coating. However, the ejection orifice forming member is made of a liquid resin, which may absorb the step or the recessed portion. Therefore, it is difficult to form the recessed portion in the surface of the ejection orifice forming member. Further, it is difficult to reduce the fluctuations in thickness of the ejection orifice forming member.